1 cent per image.
Exactly 1024×1024, stretched to fill the square when it has to. JPEG or PNG. Up to 1000.
Make a batch the same 1024-pixel square, stretching when the photo is not already square.
Up to 1000 files at a time. With 5 or fewer, you download each one on its own. With more than 5, you see the first 5 and get all of them together in one ZIP.